Expansion Valve: Testing and Inspection

1. Connect manifold gauge set.
2. Run engine at 2000 rpm for at least five minutes and check the high pressure gauge reading.
a. Gauge readings should be 185 - 213 psi (1275 - 1471 kPa). If not, verify refrigerant charge is correct, compressor belt tension is OK, and the system is free from exterior obstructions, e.g. leaves or paper on the condenser fins.
b. If the low-side gauge readings drop to zero and the receiver/drier's inlet and outlet sides have no temperature difference, the expansion valve is probably faulty.